First of all, recognise that listening has to be learned. We teach children to speak and adults to speak in public, but we don't teach listening - so it's hardly surprising that most of us are not very good at it.
Next, appreciate that listening takes time - but, as the Greek philosopher Epictetus put it: “God gave man two ears but only one mouth that he might hear twice as much as he speaks.”
Normally, listen while seated. This will show commitment and aid concentration.
If you expect the conversation to last some time and/or to be sensitive, isolate yourself. So, if you're in an office, have the door nearly but not totally closed (so that you have privacy but your intentions are not misunderstood), advise colleagues that you're not available, and switch off your mobile.
Compose yourself physically. So don't twist your legs around each other or cross your arms, but instead be loose and open.
Compose the space physically - if it is your space as opposed to someone else's office or a café. So try to have a quiet, welcoming space with fruit, flowers or pot pourri.
Now listen with an open mind and an open heart - free of preconceptions and prejudices.
To listen effectively, concentrate totally on the speaker and what is being said. Avoid the temptation to be preparing mentally an immediate reply.
Give visual encouragement to the speaker - such as facing the speaker, offering eye contact, and indulging in mild head nodding.
Give oral encouragement to the speaker - such as, in conversation, periodically using words like "yes", "I see", "I understand" or even just sounds like "mmm" or "ah".
Don't interrupt. Let the speaker tell the story in his/her own words and at his/her own pace.
Don't rush to fill a silence. Often a speaker will be more forthcoming or revealing if he/she is given a chance to compose his/her thoughts.
Beware of making judgements and instead ask open questions - so not "You must have hated that", but "How did you feel about that?"
If you want to be sure that you've understood a particular point, reflect it back to the speaker and check that this really is what he/she meant.
When you want to remember a detail - such as a name or meeting arrangements - repeat immediately and aloud whatever it is you wish to remember. Then, as soon as it is convenient, write it down.
If you're listening at a meeting or a conference, take notes. This will aid your concentration at the time and assist your recall after the event.
When someone says 'Can I talk to you sometime?' try to make the time immediately to have a conversation. If someone has a worry or a suggestion or just a query, the sooner one can address it, the better for them (and, if you have a relationship with that person such as parent, partner or manager, probably for you).
Finally - and perhaps ironically - the last lesson on effective listening is knowing when to stop listening. There are occasions when the wise and proper thing to do is not to listen. If a friend or colleague abuses your willingness to listen by taking an excessive amount of your time or taking time which is inappropriate, you need to say so, politely but firmly. If a colleague is simply using you to pass on negative gossip, you should explain that you're not in the business of running down colleagues or passing on tittle-tattle. If a colleague raises a work issue that should be taken up with that colleague's line manager or trade union, you should say so. If the issue raised involves a medical condition or pyschological problem, you should encourage the person concerned to seek professional help. You are a good listener - but you are not there to be 'dumped on' and you are certainly not a doctor or a psychotherapist.
“Let every man be swift to hear, and slow to speak” (James 1:19).
